Group III-V compound semiconductors such as GaN and AlGaN are widely used in optoelectronics and for electronic devices by virtue of many advantages thereof, for example, a wide and easily adjustable band gap energy.
In particular, light emitting devices, such as light emitting diodes and laser diodes, which use a Group III-V or Group II-VI compound semiconductor material, are capable of rendering various colors, such as red, green, blue, and ultraviolet, by virtue of the development of thin-film growth technologies and device materials, are capable of producing white light at high efficiency using fluorescent materials or through color mixing, and have advantages such as low power consumption, semi-permanent lifespan, fast response speed, safety, and environmental friendliness as compared to conventional light sources, such as fluorescent lamps and incandescent lamps.
Therefore, such light emitting devices are increasingly applied to transmission modules of optical communication units, light emitting diode backlights as a replacement for cold cathode fluorescent lamps (CCFLs) constituting backlights of liquid crystal display (LCD) devices, lighting apparatuses using white light emitting diodes as a replacement for fluorescent lamps or incandescent lamps, headlights for vehicles, and traffic lights.
In a conventional light emitting device, a light emitting structure including an n-type semiconductor layer, an active layer and a p-type semiconductor layer is formed, and the conventional light emitting device emits light having energy determined by the intrinsic energy band of the material of the active layer when electrons injected into the active layer via the n-type semiconductor layer combine with holes injected into the active layer via the p-type semiconductor layer.
Attempts to form pixels while reducing the cross-sectional area of the light emitting structure have been made, but it is difficult to realize an ultrathin unit pixel because the thickness of each light emitting structure is too large.
That is, the above-mentioned light emitting structure is grown on a substrate formed of sapphire or the like; however, in a horizontal-type light emitting diode, in which a substrate is left as it is after growth of the light emitting structure, or in a vertical-type light emitting diode, in which a substrate is removed after a metal support is coupled to a portion of the light emitting structure, it is difficult to realize ultrathin pixels because the substrate or the metal support has a large thickness.